The invention relates to analyzing an acquired arrangement of object locations.
The usefulness of a product expected to include items or attributes in a predetermined arrangement is diminished by a defect relating to the arrangement. If the product is meant to be a component in another product, this defect may ruin the other product.
For this reason, products incorporating such items or attributes in such predetermined arrangements may be inspected for compliance with some standard. Examples of products appropriate for inspection include ball grid array devices, micro-ball grid arrays, flip chips, and chip-scale packages (together called "BGAs"). The contacts (i.e., electrical terminals) of a BGA are metallic balls that are mounted on one side of the device for forming electrical connections between an integrated circuit within the BGA and a printed circuit board.
The standard used in the inspection is typically created by manual entry of coordinates, by "golden template" sampling, by derivation from computer-aided design ("CAD") data, or by some combination of these. According to the manual entry technique, a human operator uses a data entry device, such as a mouse or a keyboard, to specify x-y coordinates for the position of each object in the arrangement. Thus, manual entry can require considerable time. In golden template sampling, the positions of the objects in the standard are taken to be the positions found in an actual implementation of an ideal arrangement (e.g., an arrangement of balls of an actual BGA device). Golden template sampling may take less time than manual entry but may provide results that are less accurate. With respect to derivation from CAD data, the positions of the objects may be determined by software that automatically selects the positions in accordance with information about design goals, if such information is available.